Optical navigation system using a single-package motion sensor

ABSTRACT

An optical navigation apparatus including a package incorporating a light source and a single die of silicon. The single die of silicon includes a photodiode array configured at the detection plane to receive the speckle pattern of the scattered light from the collection optics, circuitry configured to process signals from the photodiode array to determine changes in position of the apparatus relative to the tracking surface, analog circuitry configured to control and drive current through the light source, interface circuitry configured to communicate position data by outputting the position data via a data interface, a microcontroller comprising a processor core and memory for storing computer-readable code and data, and a system bus configured to communicate instructions and data between the microcontroller and said digital, analog, and interface circuitries. Other embodiments, aspects and features are also disclosed.

RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional applicationSer. No. 12/009,863 filed Jan. 22, 2008, now U.S. Pat. No. 8,031,176issued Oct. 4, 2011 which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The present invention relates generally to apparatus and methods ofpackaging optical navigation sensors.

BACKGROUND OF THE INVENTION

Pointing devices, such as computer mice or trackballs, are utilized forinputting data into and interfacing with personal computers andworkstations. Such devices allow rapid relocation of a cursor on amonitor, and are useful in many text, database and graphical programs. Auser controls the cursor, for example, by moving the mouse over asurface to move the cursor in a direction and over distance proportionalto the movement of the mouse. Alternatively, movement of the hand over astationary device may be used for the same purpose.

Computer mice come in both optical and mechanical versions. Mechanicalmice typically use a rotating ball to detect motion, and a pair of shaftencoders in contact with the ball to produce a digital signal used bythe computer to move the cursor. One problem with mechanical mice isthat they are prone to inaccuracy and malfunction after sustained usedue to dirt accumulation, and such. In addition, the movement andresultant wear of the mechanical elements, particularly the shaftencoders, necessarily limit the useful life of the device.

One solution to the above-discussed with mechanical mice problems hasbeen the development of optical mice. Optical mice have become verypopular because they are more robust and may provide a better pointingaccuracy.

One approach used for optical mice relies on a light emitting diode(LED) illuminating a surface at or near grazing incidence, atwo-dimensional CMOS (complementary metal-oxide-semiconductor) detectorwhich captures the resultant images, and software that correlatessuccessive images to determine the direction, distance and speed themouse has been moved. This technology typically provides high accuracybut suffers from a complex design and relatively high image processingrequirements. In addition, the optical efficiency is low due to thegrazing incidence of the illumination.

Another approach differs from the standard technology in that it uses acoherent light source, such as a laser. Light from a coherent sourcescattered off of a rough surface generates a random intensitydistribution of light known as speckle.

SUMMARY

One embodiment disclosed relates to an optical navigation apparatusincluding a package incorporating a light source for generating lightand a single die of silicon including circuitry configured thereon. Theapparatus further includes illumination optics configured to illuminatea tracking surface with the light from the light source, and collectionoptics configured to collect scattered light from the tracking surfaceso as to form a speckle pattern at a detection plane. The single die ofsilicon includes a photodiode array configured at the detection plane toreceive the speckle pattern of the scattered light from the collectionoptics, circuitry configured to process signals from the photodiodearray to determine changes in position of the apparatus relative to thetracking surface, analog circuitry configured to control and drivecurrent through the light source, interface circuitry configured tocommunicate position data by ontputting the position data via a datainterface, a microcontroller comprising a processor core and memory forstoring computer-readable code and data, and a system bus configured tocommunicate instructions and data between the microcontroller and saiddigital, analog, and interface circuitries.

Other embodiments, aspects and features are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and various other features and advantages of the presentdisclosure are understood more fully from the detailed description thatfollows and from the accompanying drawings, which, however, should notbe taken to limit the appended claims to the specific embodiments shown,but are for explanation and understanding only.

FIG. 1 is a schematic diagram of an optical navigation system using asingle-package motion sensor and a light source in accordance with anembodiment of the invention.

FIG. 2 is a layout of a printed circuit board for an optical navigationsystem in accordance with an embodiment of the invention.

FIG. 3 is a side view showing a single-package motion sensor for anoptical navigation system in accordance with an embodiment of theinvention.

FIG. 4 is a die mount layout for a single-package motion sensor and alight source in accordance with an embodiment of the invention.

FIG. 5 is a schematic diagram of a two-dimensional comb array inaccordance with an embodiment of the invention.

FIG. 6 is a cross-sectional diagram showing an optical navigationapparatus with a lens (illumination optic) integrated into a package inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of an optical navigation system using asingle-package motion sensor (a packaged silicon die) 102 and a lightsource 104 in accordance with an embodiment of the invention. Althoughthe light source 104 is shown separate from the silicon die of themotion sensor 102 in FIG. 1, the light source 104 may be integrated withthe sensor package (for example, bonded to the surface of the silicondie of the motion sensor) such that no calibration or alignment isneeded during assembly of the computer mouse.

In the illustrated embodiment, the light source 104 is a VCSEL(vertical-cavity surface-emitting laser). For example, the VCSEL may beimplemented so as to output laser light at a wavelength of between 840to 870 nm with about 0.5 mW of power at room temperature.

The motion sensor 102 has multiple components integrated onto a singlepackaged silicon die. In the illustrated embodiment, the single-packagemotion sensor 102 includes a laser navigation sensor component 110, aPSoC® (Programmable System-On-Chip) Core 120, a capacitive sensingsystem (CapSense System) 130, system resources 140, a system bus 150,and global analog interconnect 152.

As shown, the system bus 150 may be configured to interconnect andcommunicate data between the laser navigation sensor component 110, thePSoC® Core 120, the capacitive sensing system (CapSense System), and thesystem resources 140. As further shown, the global analog interconnect152 may be configured to interconnect and communicate analog signalsbetween analog input ports (see Ports 0, 1 and 2 in FIG. 1) and thecapacitive sensing system 130.

The laser navigation sensor 110 includes both digital 114 and analog 116circuitry. The analog circuitry 116 includes driver circuitry (VCSELDriver) to drive the light source (VCSEL 104) and also the photodiodearray (PDA). In one embodiment of the invention, the PDA may be wired asa comb array. In particular, the PDA may be wired as a two-dimensionalcomb array, as described further below in relation to FIG. 5.

As shown, the PSoC core 120 may include a CPU (central processing unit)core 122, memory components (including, for example, SRAM or staticrandom access memory for data storage, SROM or supervisory read onlymemory, and flash nonvolatile memory), an interrupt controller, sleepand watchdog timers, and multiple clock sources 124. The CPU core 122may be configured, for example, as an 8-bit Harvard architectureprocessor with processor speeds running to 24 MHz.

The multiple clock sources 124 may include, for example, an internalmain oscillator (IMO) which is configured to output clock signals at 6,12, and 24 MHz. The multiple clock sources 124 may also include, forexample, an internal low-speed oscillator (ILO) which is configured tooutput a clock signal at 32 kHz for use by the watchdog and sleeptimers.

As further shown, digital and analog inputs and outputs may be providedby way of input/output ports (see Port 0, Port 1 and Port 2). A boostregulator and a 1.8/2.5/3.0 volt low dropout (LDO) regulator may also beprovided.

In accordance with an embodiment of the invention, the digital inputsand outputs are reconfigurable using internally-stored firmware (i.e.computer-readable instructions stored in non-volatile memory), and themicrocontroller is configured to process the signals from thereconfigurable digital inputs. In further accordance with an embodimentof the invention, the analog inputs and outputs are also reconfigurableusing internally-stored firmware (i.e. computer-readable instructionsstored in non-volatile memory).

In one implementation, the reconfigurable inputs are configured toreceive button press data. In another implementation, the reconfigurableinputs are configured to receive scroll wheel input data. Thereconfigurable outputs may be configured, for example, to control andpower external indicators, such as light emitting diode indicators.Battery charging and monitoring may be implemented by configuration ofthe analog inputs and outputs for such charging and monitoring.

The capacitive sensor system 130 is configured to perform capacitivesensing and scanning using comparator circuits without requiringexternal components. In one embodiment, capacitive sensing may beconfigurable on each of the input/output ports. The capacitive sensorsystem 130 includes a capacitive sensor module 132 which iscommunicatively coupled to the system bus 150 and is further coupled toreceive a clock signal or signals from the multiple clock sources 124and to receive an analog reference signal. An analog multiplexercomponent couples the capacitive sensing module 132 to the global analoginterconnect 152.

In accordance with one embodiment, the capacitive sensing system 130 maybe configured to process signals and output data to said reconfigurableinputs. In one implementation, the capacitive sensor circuitry is usedto process signals for scroll wheel operation. In anotherimplementation, the capacitive sensor circuitry is used to wake-up amouse device upon a user touch. In other words, the capacitive sensorcircuitry may be used to sense the proximity or touch of a user's handto trigger the mouse device's transition from a low-power state to anactive state.

The system resources 140 may include, for example, circuitry for afull-speed Universal Serial Bus (FS USB) interface, internal voltagereferences, system resets, power on reset (POR) and low voltagedetection (LVD). In addition, the system resources 140 may also include,for example, Serial Peripheral Interface (SPI) master and slave circuits(which may be configurable, for example, between 46.9 kHz to 3 MHz),programmable timers (for example, three 16-bit timers), and digitalclock circuits.

FIG. 2 is a layout of a printed circuit board (PCB) 200 for an opticalnavigation system in accordance with an embodiment of the invention. ThePCB layout shows a placement of the packaged silicon die for the motionsensor 102 and associated contact pads 202 for input/output, power, andso forth. In addition, opening features 204 for connecting aself-aligning snap-on molded optic 304 (see FIG. 3) is shown, as well asalignment features 206 for aligning the molded optic 304 to the PCB 200.Keep out zones 208 which relate to the molded optic 304 are also shown.Also shown are horizontal dimensions (going from −12.34 mm to +6.23 mm)and vertical dimensions (going from −2.88 mm to +9.52 mm).

FIG. 3 is a side view showing a single-package motion sensor for anoptical navigation system in accordance with an embodiment of theinvention. The packaged silicon die 102 is shown mounted to the printedcircuit board 200. The optical navigation apparatus is configured sothat the printed circuit board 200 is a predetermined distance (in thiscase, 6 mm) from a tracking surface 302 when the apparatus is in normaloperation. As shown, a molded optic (i.e. a molded lens) 304 is attachedto the printed circuit board 200.

FIG. 4 is a die mount layout for a single-package motion sensor 102 anda light source (in this case, a VCSEL) 104 in accordance with anembodiment of the invention. Of particular interest, an optical aperture402 for the VCSEL is shown in the die mount layout. In accordance withan embodiment of the invention, this optical aperture 402 is configuredto control a spatial frequency distribution of the laser speckledetected by the photodiode array. Also shown are horizontal and verticaldistances (in mils, a mil being 0.001 inches) from the center of eachdie to an alignment feature on the die mount.

FIG. 5 is a schematic diagram of a two-dimensional comb array inaccordance with an embodiment of the invention. An exampletwo-dimensional array 502 of photodiode detector elements is shown. The2D array 502 is made up of 64 sub-arrays 504 organized in an 8-by-8matrix. An expanded view of one such sub-array 504 is shown on the leftside of the figure.

Each sub-array 504 comprises 16 detector elements organized in a 4-by-4matrix. The 16 detector elements in each sub-array 504 are eachidentified as being a member of one of eight groups of elements. Thegroup number associated with each detector element of each sub-array 504is shown by the number (1, 2, 3, 4, 5, 6, 7, or 8) labeling the elementin the expanded view. The signals from each group are electricallyganged together for the entire array 502. The resultant group signals(numbered 1 through 8) are output from the array 502 (as shown on theright side of the figure).

Differential circuitry 506 is used to generate differential signals frompairs of the group signals. A first differential signal CC is generatedby the difference of signals 1 and 2. A second differential signal SC isgenerated by the difference of signals 3 and 4. A third differentialsignal CS is generated by the difference of signals 5 and 6. A fourthdifferential signal SS is generated by the difference of signals 7 and8. These four differential signals contain the information of thein-phase and quadrature signals in the x and y directions.

One embodiment disclosed relates to an optical navigation apparatusincluding a package incorporating a light source 104 for generatinglight and a single die of silicon 102 including circuitry configuredthereon. The apparatus further includes illumination optics (moldedoptic 304) configured to illuminate a tracking surface with the lightfrom the light source, and collection optics (also molded optic 304)configured to collect scattered light from the tracking surface so as toform a speckle pattern at a detection plane. The single die of silicon102 includes a photodiode array (PDA) configured at the detection planeto receive the speckle pattern of the scattered light from thecollection optics, digital circuitry 114 configured to process signalsfrom the photodiode array to determine changes in position of theapparatus relative to the tracking surface, analog circuitry 116configured to control and drive current through the light source,interface circuitry (for example, full-speed USB) configured tocommunicate position data by outputting the position data via a datainterface, a microcontroller comprising a processor core 122 and memoryfor storing computer-readable code and data, and a system bus 152configured to communicate instructions and data between themicrocontroller and said digital, analog, and interface circuitries.

FIG. 6 is a cross-sectional diagram of an optical navigation apparatusover a surface in accordance with an embodiment of the invention. Asshown, the optical navigation apparatus includes a printed circuit board200, a silicon die motion sensor 102, and a laser emitter 104. The laser104 emits coherent light 606 towards the scattering surface 302.

In addition, this embodiment includes a molded transparent plasticencapsulant 602 that is part of the packaging of the silicon die motionsensor 102, the packaging being mounted to the PCB 200. The transparentencapsulant 602 also embodies the collimating lens 604 as an integralpart of the packaging of the silicon die motion sensor 102 and the laser104. Note that collection optics are not necessarily needed in thisarchitecture as the scattered light may be detected by the sensor 102without any imaging lenses for that purpose. The transparent encapsulant602 also serves to protect the laser emitter 104 and the silicon diemotion sensor 102. In another implementation, the collimating lens 604may be a part which is plugged into the packaging of the silicon diemotion sensor 102. In accordance with a specific implementation, thecollimating lens 604 is configured in proximity to the laser 104 so asto receive the coherent light and to form a collimated illumination beam606 therefrom.

The foregoing description of specific embodiments and examples of theinvention have been presented for the purpose of illustration anddescription, and although the invention has been described andillustrated by certain of the preceding examples, it is not to beconstrued as being limited thereby. They are not intended to beexhaustive or to limit the invention to the precise forms disclosed, andmany modifications, improvements and variations within the scope of theinvention are possible in light of the above teaching. It is intendedthat the scope of the invention encompass the generic area as hereindisclosed, and by the claims appended hereto and their equivalents.

What is claimed is:
 1. A user interface apparatus comprising: a packagethat includes a single die including thereon: optical navigation sensorcircuitry configured to translate changes in a light pattern propagatedfrom a tracking surface relative to which the user interface apparatusis moved into data representing motion of the user interface apparatusrelative to the tracking surface; and capacitive sensor circuitryconfigured to sense a user's hand proximate to a surface of the userinterface apparatus to process signals and output data relative thereto,the capacitive sensor circuitry configured to perform capacitive sensingwithout components external to the single die.
 2. The user interfaceapparatus of claim 1, wherein the optical navigation sensor circuitrycomprises a photodiode array to detect the light pattern propagated ontothe photodiode array from the tracking surface, and a signal processorto translate changes in the light pattern propagated onto the photodiodearray into data representing motion of the user interface apparatusrelative to the tracking surface.
 3. The user interface apparatus ofclaim 1, further comprising a light source to illuminate at least aportion of tracking surface, and wherein the optical navigation sensorcircuitry further includes driver circuitry to drive the light source.4. The user interface apparatus of claim 3, wherein the light source isincluded within the package.
 5. The user interface apparatus of claim 1,wherein the capacitive sensor circuitry includes circuitry configured tosense proximity of the user's hand to trigger a transition of the userinterface apparatus from a low-power state to an active state.
 6. Theuser interface apparatus of claim 1, wherein the user interfaceapparatus comprises a mouse including buttons, and wherein thecapacitive sensor circuitry is configured to sense pressing of buttonson the mouse.
 7. The user interface apparatus of claim 1, wherein thelight pattern comprises a speckle pattern formed from light scatteredfrom the tracking surface.
 8. An optical navigation apparatuscomprising: a package that includes a single die including thereon:optical navigation sensor circuitry configured to translate changes in alight pattern propagated from a tracking surface relative to which theoptical navigation apparatus is moved into data representing motion ofthe optical navigation apparatus relative to the tracking surface;capacitive sensor circuitry configured to sense a user's hand proximateto a surface of the optical navigation apparatus to process signals andoutput data relative thereto, the capacitive sensor circuitry configuredto perform capacitive sensing without components external to the singledie; and a microcontroller to process signals from the opticalnavigation sensor circuitry and capacitive sensor circuitry, themicrocontroller including a processor core, memory for storingcomputer-readable code and data, and a number of inputs and outputs forthe optical navigation apparatus.
 9. The optical navigation apparatus ofclaim 8, wherein the optical navigation sensor circuitry comprises aphotodiode array to detect the light pattern propagated onto thephotodiode array from the tracking surface, and a signal processor totranslate changes in the light pattern propagated onto the photodiodearray into data representing motion of the optical navigation apparatusrelative to the tracking surface.
 10. The optical navigation apparatusof claim 8, further comprising a light source to illuminate at least aportion of tracking surface, and wherein the optical navigation sensorcircuitry further includes driver circuitry to drive the light source.11. The optical navigation apparatus of claim 8, wherein the capacitivesensor circuitry includes circuitry configured to sense proximity of theuser's hand to trigger a transition of the optical navigation apparatusfrom a low-power state to an active state.
 12. The optical navigationapparatus of claim 8, wherein the optical navigation apparatus comprisesa mouse including buttons, and wherein the capacitive sensor circuitryis configured to sense pressing of buttons on the mouse.
 13. The opticalnavigation apparatus of claim 8, wherein the number of inputs andoutputs are reconfigurable using computer-readable code stored in thememory of the microcontroller.
 14. The optical navigation apparatus ofclaim 8, wherein the light pattern comprises a speckle pattern formedfrom light scattered from the tracking surface.
 15. A method ofmanufacturing an apparatus comprising: providing a light source toilluminate a tracking surface; providing a single die including thereonoptical navigation sensor circuitry comprising a photodiode array todetect a light pattern propagated onto the photodiode array from thetracking surface, and a signal processor to translate changes in thelight pattern propagated onto the photodiode array into datarepresenting motion of the apparatus relative to the tracking surface,capacitive sensor circuitry comprising circuitry to sense user's handproximate to a surface of the apparatus to process signals and outputdata relative thereto without components external to the single die, anda microcontroller to process signals from the optical navigation sensorcircuitry and capacitive sensor circuitry, the microcontroller includinga processor core, memory for storing computer-readable code and data,and a number of inputs and outputs for the apparatus; and packaging thesingle die, wherein the packaging incorporates illumination opticsconfigured to illuminate the tracking surface with the light from thelight source.
 16. The method of claim 15, wherein providing the singledie including optical navigation sensor circuitry comprises providingoptical navigation sensor circuitry configured to drive the lightsource.
 17. The method of claim 15, wherein providing the single dieincluding capacitive sensor circuitry comprises providing capacitivesensor circuitry configured to sense proximity of the user's hand totrigger a transition of the apparatus from a low-power state to anactive state.
 18. The method of claim 15, wherein the packagingincorporates illumination optics configured to illuminate the trackingsurface with the light from the light source.
 19. The method of claim15, wherein the light pattern comprises a speckle pattern formed fromlight scattered from the tracking surface.
 20. The method of claim 15,further comprising configuring the number of inputs and outputs usingcomputer-readable code stored in the memory of the microcontroller.